Comparison between Mach 2 rarefied airflow modification by an electrical discharge and numerical simulation of airflow modification by surface heating

摘要

This study is devoted to numerical and experimental investigations about the influence of an electrical discharge over a flat plate immersed in a rarefied Mach 2 airflow. Regarding the experimental work, a negative dc discharge is created by applying a potential difference gap between two spanwise aluminum electrodes flush mounted on the plate. The electrode placed close to the leading edge is connected to the negative dc voltage, the second one is grounded. The influence due to the presence of the electric discharge is investigated with a glass Pitot tube by measuring the pressure proles above the flat plate. These experimental results are compared to the numerical work, where the effect of a surface temperature increase is simulated. Different effects can be attributed to the electrical discharge: the ionization of the gas above the plate with the creation of charged species, the acceleration of the positive charged species, the heat of the gas volume above the flat plate, and the heating of the surface of the flat plate. The Pitot probe measurements have shown a thickening of the boundary layer and the increasing of the angle of the shock wave, and the simulation of the surface temperature increase shows the same effect. These arguments let to think that the heating effect due to the temperature increase in the flat plate is the major one among the other effects mentioned above.